System and method for orienting a baffle proximate an array of fans that cool electronic components

ABSTRACT

A baffle is provided proximate an array of fans used to cool electronic components. The baffle may assume different orientations with respect to the array of fans.

BACKGROUND

In the art of computing, it is desirable to provide redundancy so that acomputer system can continue to function after the failure of acomponent. Cooling redundancy allows a computer system to continue tofunction when a cooling component, such as a cooling fan, fails.

In the prior art, cooling redundancy is provided in many forms, such asproviding additional cooling fans, rotating remaining fans at a higherspeed in the event of a fan failure, and mounting cooling fanscoaxially. However, each cooling fan occupies a unique physicallocation, and when a fan fails, it can be a challenge to replicate theairflow lost at the location of the failed fan.

BRIEF DESCRIPTION OF THE DRAWINGS

The Figures depict embodiments, examples, implementations, andconfigurations of the invention, and not the invention itself.

FIG. 1 is a block diagram of a typical system comprising boards andcooling fans.

FIG. 2 shows a block diagram representing one of the boards of FIG. 1 asa server blade.

FIG. 3 is a block diagram of the system of FIG. 1 in which a movablebaffle has been added, in accordance with examples of the presentinvention.

FIG. 4 shows the system of FIG. 3 after a fan farthest from the bafflehas failed, and the baffle has been oriented at 45° toward the failedfan, in accordance with examples of the present invention.

FIG. 5 shows the system FIG. 3 after a fan adjacent to the baffle hasfailed, with the baffle oriented at 67.5° toward failed fan, inaccordance with examples of the present invention.

FIG. 6 shows the system of FIG. 1 with two baffles and a failed fan,with the baffle closer to the failed fan oriented at 50° toward the fan,and the baffle farther from the failed fan oriented at 80° toward fan,in accordance with examples of the present invention.

FIG. 7 is a block diagram of an example of the present invention, andincludes a baffle control unit, two baffles, a baffle positioning unit,temperature sensors, and fans, in accordance with examples of thepresent invention.

FIG. 8 shows a flow chart that illustrates a how a single baffle iscontrolled to respond to a fan failure, in accordance with examples ofthe present invention.

FIG. 9 shows a flow chart illustrates how two baffles are controlled torespond to a fan failure, in accordance with examples of the presentinvention.

FIG. 10 shows a flow chart that illustrates a how a single baffle iscontrolled to respond to a board exceeding a temperature threshold, inaccordance with examples of the present invention.

FIG. 11 shows a flow chart that illustrates how two baffles arecontrolled to respond to a board exceeding a temperature threshold, inaccordance with examples of the present invention.

DETAILED DESCRIPTION

In the foregoing description, numerous details are set forth to providean understanding of the present invention. However, it will beunderstood by those skilled in the art that the present invention may bepracticed without these details. While the invention has been disclosedwith respect to a limited number of embodiments and examples, thoseskilled in the art will appreciate numerous modifications and variationstherefrom. It is intended that the appended claims cover suchmodifications and variations as fall within the true spirit and scope ofthe invention.

Examples of the present invention relate to arrays of cooling fans, withone or more movable baffles located proximate the array of cooling fans.When a cooling fan fails, the baffle is moved to deflect air in thedirection of the failed fan and expose additional cards to the remainingcooling fans.

FIG. 1 is a block diagram of a typical system 10 comprising boards B1,B2, B3, B4, B5, B6, B7, and B8, and fans F1, F2, F3, F4, F5, and F6.Cooling air is drawn in by the fans F1-F6 and is routed over the boardsB1-B8 in the direction shown by the arrows. Heated air exits the rear ofsystem 10.

Since the fans are linearly aligned with the boards, and the resistanceto airflow is relatively even along the boards, the airflow tends toflow relatively straight, as indicated by the arrows.

System 10 is shown generically, and may represent any system havingcircuit boards cooled by fans. One common configuration is a bladeserver, with each board representing a blade. FIG. 2 shows a blockdiagram representing board B1 as a server blade.

In FIG. 2, board B1 includes a bus 12. Coupled to bus 12 are one or moreCPUs 14, core logic 16, system memory 18, and network interfacecontroller 20. Also shown is power unit 22, which receives externalpower and distributes power to the components of board B1. Forsimplicity, the power connections to the components are not shown inFIG. 2.

Although bus 12 is shown generically as a single bus, those skilled inthe art will recognize that typically a variety of busses and fabricsare used to connect the components shown in FIG. 2. CPUs 14 mayrepresent a single CPU, multiple CPUs in individual integrated circuit(IC) packages, multiple CPU cores in a discrete IC package, or anycombination of these elements. Core logic 16 represents the core logicthat couples CPUs 14, system memory 18, and network interface controller20. In some architectures, core logic 16 includes a Northbridge and aSouthbridge. However, other architectures are known in the art. Forexample, in some architectures, the memory controller is provided in theCPU. For the purposes of describing embodiments of the presentinvention, core logic 16 also includes other components found in atypical computer system, such as firmware and I/O components, diskcontrollers, USB ports, video controllers, and the like. In a serverblade, some of these components may not be utilized. Furthermore,persistent storage, such as hard disk drives and solid state drives, isnot shown in FIG. 2. While some blades include persistent storage, oftenstorage is provided elsewhere, with the storage accessed via networkinterface controller 20, or a storage interface, such as a SCSIcontroller.

Note that a blade server may also have boards that perform otherfunctions, such as boards dedicated to managing network I/O and storage,or a board that performs functions associated with a service processor.In other systems, system 10 may have boards that perform otherfunctions, such as video processing in a video application, or patientmonitoring in a medical application. Further description of suchapplications is not necessary for an understanding of examples of thepresent invention.

Returning to FIG. 1, if one of the fans F1-F6 fails, the airflow fromthe remaining fans will continue to provide cooling, but the coolingwill not be even across boards B1-B8. As an example, consider Table 1,which shows temperature measured at each board B1-B8 during normaloperation of a typical system 10 with all fans F1-F6 operating.

TABLE 1 Ambient B1 B2 B3 B4 B5 B6 B7 B8 25.0° C. 61.0° C. 57.8° C. 61.5°C. 61.0° C. 64.6° C. 60.2° C. 58.1° C. 72.3° C.

Now assume that fan F1 has failed. The temperatures measured at eachboard are shown below in Table 2.

TABLE 2 Ambient B1 B2 B3 B4 B5 B6 B7 B8 25.0° C. 104.3° C. 78.4° C.55.3° C. 60.7° C. 62.0° C. 59.9° C. 57.9° C. 72.7° C.

As can be seen by comparing Tables 1 and 2, all boards are still beingcooled after the failure of fan F1. However, the cooling is much lesseven, with boards B1 and B2 proximate failed fan F1 having highertemperatures.

FIG. 3 is a block diagram of system 10 of FIG. 1 in which a baffle 24has been added, in accordance with examples of the present invention.The baffle may be angled toward a failed fan to provide additionalcooling for the area normally cooled by the failed fan. Furthermore, thebaffle may be angled for other reasons, such as providing additionalcooling for a board that is running hotter than the other boards. Table3 shows temperatures measured at each board when all fans F1-F6 areoperating normally, with baffle 24 oriented at 90° with respect to fansF1-F6.

TABLE 3 Ambient B1 B2 B3 B4 B5 B6 B7 B8 25.0° C. 59.9° C. 58.1° C. 59.1°C. 62.1° C. 60.5° C. 60.5° C. 58.2° C. 72.9° C.

FIG. 4 shows system 10 of FIG. 3 after fan F1 has failed, and baffle 24has been oriented at 45° toward failed fan F1. Note that angles oforientation discussed herein are with reference to the array of fans.For example, a 90° orientation orients the baffle perpendicular to thearray of fans, and an 80° orientation toward a failed fan moves thebaffle 10° toward the failed fan. Furthermore, angles of orientationtoward a failed fan or board may be referred to as being greater or lessthan other angles. In general, these comparisons are made with respectto the magnitude of deflection toward the fan or board, so a bafflehaving an 80° orientation toward a failed fan in either direction has agreater angle of orientation than a baffle having a 90° orientation.Similarly, a baffle having an 80° orientation toward a failed fan has asmaller angle of orientation than a baffle having a 45° orientationtoward a failed fan

As can be seen in FIG. 4, baffle 24 directs airflow from fans F3 and F2toward the failed fan F1. Furthermore, the orientation of baffle 24provides additional exposure of boards B3 and B4 to fans F4-F6, therebyallowing fans F4-F6 to replace some of the airflow being diverted fromfan F3 by baffle 24. Table 4 shows temperatures measured at each boardwhen fan F1 has failed, fans F2-F6 are operating normally, and baffle 24oriented at 45° toward failed fan F1.

TABLE 4 Ambient B1 B2 B3 B4 B5 B6 B7 B8 25.0° C. 89.4° C. 55.6° C. 53.8°C. 80.7° C. 60.0° C. 59.9° C. 57.7° C. 73.0° C.

As discussed above, Table 2 shows measured temperatures of each boardafter fan F1 has failed without the example embodiment of the presentinvention. Comparing Tables 2 and 4, one can see that the 45°orientation of baffle 24 has lowered the temperature of board B1 by14.8° C., and board B2 by 22.8° C. The temperature of board B3 islowered by a relatively small 1.5° C. The temperature of board B4actually increases from 60.7° C. to 80.7° C., but this increase isacceptable and board B3 is still running cooler than board B1. Board B5also runs a relatively small 2° C. hotter, and the temperatures atboards B6-B8 remain relatively constant (within 0.3° C.). After a fanfailure, the boards proximate the failed fan suffer the highest risk ofrunning hot. As Tables 2 and 4 demonstrate, examples of the presentinvention redistribute the airflow from the remaining fans to cause theother boards to help shoulder the burden of the failed fan, therebyminimizing the risk of the boards proximate the failed fan overheatingand failing until the failed fan can be replaced.

A failure of a fan at the end of an array of fans, as shown in FIG. 4,represents the most challenging fan failure since there is only oneimmediately adjacent fan to provide airflow in the area of the failedfan. According, a failure of a fan not on the end is less critical.

FIG. 5 shows system 10 after fan F4 has failed, with baffle 24 orientedat 67.5° toward fan F4. Since fans F3 and F5 are adjacent to the failedfan F4, a smaller deflection of baffle 24 is sufficient to redistributeairflow among the boards.

As mentioned above, a failure of a fan at an end of an array of fans ischallenging because there are not two adjacent functioning fans. Such afailure is also challenging because the end fans are the farthest fansfrom baffle 24 in the examples shown in FIGS. 3-5. The example of theinvention shown in FIG. 6 better addresses this challenge.

FIG. 6 shows system 10 with two baffles. Baffle 26 is positioned betweenfans F2 and F3, and baffle 28 is positioned between fans F4 and F5.Accordingly, there is a baffle closer to each of the end fans F1 and F6.In FIG. 6, fan F1 has failed. Since baffle 26 is closer to fan F1,baffle 26 is oriented at 50° toward fan F1, and baffle 28 is oriented at80° toward fan F1. Since baffle 26 is closer to fan F1, more airflow isdeflected toward board B1, and the deflection of baffle 28 helpscompensate for the loss of airflow to board B3. Accordingly, the exampleshown in FIG. 6 is able to distribute more evenly the airflow of theremaining fans to the boards.

The most desirable angles of orientation can be found by experimentationof the system designer by simulating fan failures and testing differentangles. Examples of the present invention may also be combined withother prior art techniques, such as rotating remaining fans faster andadjusting workloads serviced by the boards.

FIG. 7 is a block diagram 30 of an example of the present invention, andincludes baffle control unit 32, baffles 26 and 28, baffle positioningunit 34, temperature sensors TS1, TS2, TS3, TS4, TS5, TS6, TS7, and TS8,and fans F1, F2, F3, F4, F5, and F6.

Baffle control unit 32 is coupled to temperature sensors TS1-TS8, witheach temperature sensor reporting the temperature of a board. Thetemperature sensors are shown generically, and represent any temperaturesensing mechanism known in the art, such as I2C bus connections that canrelay CPU temperatures from internal temperature sensors in the CPU ICs.As will be discussed below, in some examples of the present invention,the baffles may be oriented to provide additional cooling to boards thatare running hotter than other boards.

Baffle control unit 32 is also coupled to fans F1-F6. Unit 32 monitorsthe fans to detect failure, and may also control fan operation.

Finally, baffle control unit 32 is coupled to baffle positioning unit34, which in turn is coupled to baffles 26 and 28. Under control ofbaffle control unit 32, baffle positioning unit 34 operates to orientbaffles 26 and 28 at a desired angle of orientation with respect to thearray of fans F1-F6. Baffle positioning unit 34 may use any appropriatepositioning mechanisms known in the art, such as stepper motors,piezoelectric motors, solenoids, voice coil actuators, and the like.Furthermore, although baffle positioning unit 34 is shown as a singleunit, it may be implemented using multiple units. For example, adiscrete positioning mechanism may be provided for each baffle.

Note that the components shown in FIG. 7 may be provided in variouselements of system 10. For example, baffle control unit 32 may beprovided as a stand-alone device. Alternatively, baffle control unit 32may be implemented as part of a service processor, or may execute as acontrol loop on one of the blades in a blade server.

FIGS. 8-11 are flow charts illustrating how the baffles may becontrolled. The actions shown in the flow charts may be implemented bybaffle control unit 32 in FIG. 7, or any other device used to controlexamples of the invention.

FIG. 8 shows a flow chart 36 that illustrates a how a single baffle iscontrolled to respond to a fan failure. Block 38 operates an array offans to direct airflow over an array of boards, with a default baffleorientation suitable for normal operation with all fans functioning. Asdiscussed above, a typical angle of orientation of the baffle withrespect to the array of fans when all fans are operating is 90°, but itmay be desirable to use a different orientation during normal operation,such as a slight deflection to provide additional cooling for a boardthat runs slightly hotter than the other boards. Control passes todecision block 40. Decision block 40 detects whether a fan has failed.If a fan has not failed, the NO branch is taken to block 38, andoperation and monitoring of the fans continues. If a fan has failed, theYES branch is taken to block 42.

At block 42, an angle of orientation of the baffle is selected based ona distance between the baffle and the failed fan, with the angle oforientation increasing with the distance. As shown in FIG. 4, a 45°deflection is used when the failed fan is the third fan from the baffle,and in FIG. 5, a 67.5° deflection is used when the failed fan isadjacent to the baffle. However, those skilled in the art will recognizethat other angles may be used. Control passes to block 44.

Block 44 signals the baffle control unit to move the baffle to theselected angle of orientation. At this point, operation continues withthe failed fan and the baffle redirects airflow to compensate for theairflow lost by the fan failure. At block 44, it may be desirable toperform other actions, such as signaling an operator that a fan hasfailed and needs to be serviced, operating remaining fans at fasterrotational speeds, or moving workloads off the boards proximate thefailed fan. Control passes back to decision block 40.

Block 40 continues to monitor for failed fans. In the unlikely eventthat a second fan fails before the first failed fan is repaired,additional steps may be performed. For example, it may be desirable toreturn the baffle to a 90° orientation. Alternatively, it may bedesirable to use the temperature monitoring techniques discussed belowwith respect to FIG. 10 to find an optimal position for the baffle tomaximize cooling in view of the failed fans. Finally, it may benecessary to reduce the workload on one or more boards, or power downone or more board, and use the baffle to maximize cooling to theremaining boards with the remaining fans.

FIG. 9 shows a flow chart 46 that illustrates how two baffles arecontrolled to respond to a fan failure. Block 48 operates an array offans to direct airflow over an array of boards, with default baffleorientations suitable for normal operation with all fans functioning.Typical angles of orientation of the baffles with respect to the arrayof fans when all fans are operating are 90°, but it may be desirable touse different orientations during normal operation, such as slightdeflections to provide additional cooling for a board that runs slightlyhotter than the other boards. Control passes to decision block 50.Decision block 50 detects whether a fan has failed. If a fan has notfailed, the NO branch is taken to block 48, and operation and monitoringof the fans continues. If a fan has failed, the YES branch is taken toblock 52.

At block 52, angles of orientation of the first and second baffles areselected based on distances between the baffles and the failed fan, withthe angle of orientation of the baffle closer to the failed fan greaterthan the angle of orientation of the baffle farther from the failed fan.If the distances are equal, the angles of orientations may be equal. Asshown in FIG. 6, a 50° orientation is used for the baffle that isclosest to the failed fan, and an 80° orientation is used for the bafflethat is farther from the failed fan. However, these orientations aremerely examples, and those skilled in the art will recognize that otherangles may be used. Control passes to block 54.

Block 54 signals the baffle control unit to move the first and secondbaffles to the selected angles of orientation. At this point, operationcontinues with the failed fan and the baffles redirecting airflow tocompensate for the airflow lost by the fan failure. In block 54, it maybe desirable to perform other actions, such as signaling an operatorthat a fan has failed and needs to be serviced, operating remaining fansat faster rotational speeds, or moving workloads off the boardsproximate the failed fan. Control passes back to decision block 50.

Block 50 continues to monitor for failed fans. In the unlikely eventthat a second fan fails before the first failed fan is repaired,additional steps may be performed. For example, it may be desirable toreturn the baffles to a 90° orientation. Alternatively, it may bedesirable to use the temperature monitoring techniques discussed belowwith respect to FIG. 11 to find an optimal position for the baffles tomaximize cooling in view of the failed fans. Finally, it may benecessary to reduce the workload on one or more boards, or power downone or more board, and use the baffles to maximize cooling to theremaining boards with the remaining fans.

FIG. 10 shows a flow chart 56 that illustrates a how a single baffle iscontrolled to respond to a board exceeding a temperature threshold.Block 58 operates an array of fans to direct airflow over an array ofboards. As discussed above, a typical orientation of 90° may be used, orother default orientations may be used. Control passes to decision block60. Decision block 60 detects whether a board has exceeded a temperaturethreshold. A designer may select a suitable threshold, such as 85° C. or90° C. that is appropriate in view of the thermal tolerances of theboards. If a board has not exceeded a temperature threshold, the NObranch is taken to block 58, and operation of the fans and monitoring ofthe board temperatures continues. If a board has exceeded a temperaturethreshold, the YES branch is taken to block 62.

At block 62, an angle of orientation of the baffle is selected based ona distance between the baffle and the board exceeding the temperaturethreshold, with the angle of orientation increasing with the distance.It may also be desirable to base the angle of orientation on themagnitude by which the measured board temperature exceeds thetemperature threshold. Control then passes to block 64.

Block 64 signals the baffle control unit to move the baffle to theselected angle of orientation. Control passes back to decision block 60,and monitoring of board temperatures and adjustment of the bafflecontinues. It may be desirable to perform other actions, such assignaling an operator that a board is running hot, operating fans atfaster rotational speeds, or moving workloads off the board that isrunning hot.

FIG. 11 shows a flow chart 66 that illustrates how two baffles arecontrolled to respond to a board exceeding a temperature threshold.Block 68 operates an array of fans to direct airflow over an array ofboards. As discussed above, a typical orientation of 90° may be used, orother default orientations may be used. Control passes to decision block70. Decision block 70 detects whether a board has exceeded a temperaturethreshold. A designer may select a suitable threshold, such as 85° C. or90° C. that is appropriate in view of the thermal tolerances of theboards. If a board has not exceeded a temperature threshold, the NObranch is taken to block 68, and operation of the fans and monitoring ofthe board temperatures continues. If a board has exceeded a temperaturethreshold, the YES branch is taken to block 72.

At block 72, angles of orientation of the first and second baffles areselected based on distances between the baffles and the board exceedingthe temperature threshold, with the angle of orientation of the bafflecloser to the board exceeding the temperature threshold greater than theangle of orientation of the baffle farther from the board exceeding thethreshold. If the distances are equal, the angles of orientations may beequal. It may also be desirable to base the angles of orientation on themagnitude by which the measured board temperature exceeds thetemperature threshold. Control passes to block 74.

Block 74 signals the baffle control unit to move the baffles to theselected angles of orientation. Control passes back to block 70, andmonitoring of board temperatures and adjustment of the bafflescontinues. It may be desirable to perform other actions, such assignaling an operator that a board is running hot, operating fans atfaster rotational speeds, or moving workloads off the board that isrunning hot.

For simplicity, the flow charts showing how to operate the baffles inthe event of fan failure and high board temperatures have been shownseparately. However, it may be desirable to combine the flowcharts. Forexample, the board temperature flow charts may be used when all fans areoperating normally, and control can pass to the failed fan flow chartswhen a fan failure is detected.

The present invention further increases reliability and redundancy insystems using an array of cooling fans. Even though a certain level ofredundancy is provided by having multiple fans, it is a challenge toreplace the airflow lost when a fan fails because the fan occupies adiscrete physical location. Examples of the present invention addressthis challenge, and also provide opportunities to direct airflow toboards that run hotter.

In the foregoing description, numerous details are set forth to providean understanding of the present invention. However, it will beunderstood by those skilled in the art that the present invention may bepracticed without these details. While the invention has been disclosedwith respect to a limited number of examples and embodiments, thoseskilled in the art will appreciate numerous modifications and variationstherefrom. It is intended that the appended claims cover suchmodifications and variations as fall within the true spirit and scope ofthe invention.

1. A system comprising: an array of fans, the array of fans includingfirst and second end fans; an array of electronic components cooled bythe array of fans; a movable baffle located between the first and secondend fans; a baffle positioning unit coupled to the movable baffle; and abaffle control unit coupled to the baffle positioning unit, wherein thebaffle control unit signals the baffle positioning unit to orient themovable baffle to a desired angle with respect to the array of fans. 2.The system of claim 1 wherein each fan of the array of fans is coupledto the baffle control unit to allow the baffle control unit to detect afailed fan of the array of fans, and in response to detecting a failedfan, the baffle control unit signals the baffle positioning unit toorient the movable baffle toward the failed fan.
 3. The system of claim2 wherein the desired angle of the movable baffle is selected based on adistance between the movable baffle and the failed fan, with the desiredangle increasing with the distance.
 4. The system of claim 1 wherein themovable baffle is a first movable baffle, and further comprising: asecond movable baffle positioned between the first and second end fansand coupled to the baffle positioning unit, wherein each fan of thearray of fans is coupled to the baffle control unit to allow the bafflecontrol unit to detect a failed fan of the array of fans, and inresponse to detecting a failed fan, the baffle control unit signals thebaffle positioning unit to orient the first or second movable baffleclosest to the failed fan towards the failed fan.
 5. The system of claim4 wherein the baffle control unit also signals the baffle positioningunit to orient the first or second movable baffle farthest from thefailed fan towards the failed fan.
 6. The system of claim 5 wherein thedesired angle is a first desired angle, the first desired angle of thefirst or second movable baffle closer to the failed fan is greater thana second desired angle of the first or second movable baffle fartherfrom the failed fan.
 7. The system of claim 1 and further comprising: anarray of temperature sensors coupled to the baffle control unit, formeasuring temperatures of electronic components of the array ofelectronic components, wherein the baffle control unit signals thebaffle positioning unit to orient the movable baffle toward anelectronic component of the array of electronic components that has ameasured temperature above a threshold.
 8. The system of claim 1 whereinthe array of electronic components comprise an array of circuit boards.9. The system of claim 8 wherein the system is a server, and the arrayof circuit boards comprise an array of server blades.
 10. A method ofproviding cooling redundancy in a server having an array of serverblades comprising: operating an array of fans to direct airflow over thearray of server blades; detecting a failed fan of the array of fans; andin response to detecting a failed fan, orienting a baffle to redirectairflow from functioning fans of the array or fans toward server bladesof the array of server blades proximate the failed fan.
 11. The methodof claim 10 wherein in response to detecting a failed fan, orienting abaffle to redirect airflow from functioning fans of the array or fanstoward server blades of the array of server blades proximate the failedfan includes: selecting an angle of orientation of the baffle based on adistance between the baffle and the failed fan, with the angle oforientation increasing with the distance.
 12. The method of claim 10wherein in response to detecting a failed fan, orienting a baffle toredirect airflow from functioning fans of the array or fans towardserver blades of the array of server blades proximate the failed fancomprises selecting a first baffle of a plurality of baffles closest tothe failed fan, and orienting the first baffle to redirect airflow fromfunctioning fans of the array or fans toward server blades of the arrayof server blades proximate the failed fan.
 13. The method of claim 10and further comprising: measuring temperatures of server blades of thearray of server blades; in response to detecting a server blade of thearrays of server blades having a measured temperature above a threshold,orienting the baffle toward the server blade having the measuredtemperature above the threshold.
 14. Readable media having computerexecutable program segments stored thereon, the computer executableprogram segments comprising: a first program segment for monitoring aplurality of fans that cool electronic components and detecting a failedfan; and a second program segment for signaling, in response todetecting a failed fan, a baffle positioning unit to orient a bafflelocated among the plurality of fans toward the failed fan.
 15. Thereadable media of claim 14 and further comprising: a third programsegment for measuring temperatures of the electronic components; and afourth program segment for signaling the baffle positioning unit toorient the baffle toward an electronic component having a measuredtemperature above a threshold.
 16. The readable media of claim 14wherein the second code segment includes code for determining an angleof orientation of the baffle based on a distance between the baffle andthe failed fan.
 17. The readable media of claim 16 wherein the angle oforientation increases with the distance.
 18. The readable media of claim14 wherein the baffle is a first baffle, and the second code segmentincludes code to orient either the first baffle or a second baffletoward the failed fan.
 19. The readable media of claim 14 wherein thebaffle is a first baffle, and the second code segment includes code toorient both the first baffle or a second baffle toward the failed fan,with a baffle closer to the failed fan having an angle orientationgreater that a baffle farther from the failed fan.